Circuit interrupter



y 1950 A. J. A. PETERSON EI'AL 2,516,018

CIRCUIT INTERRUPTER 2 Sheets-Sheet 1 Filed Nov. 7, 1946 INVENTOR$ ATTORNEY I 8 6 7 a a a M 296 6 A 3 a a 1 w l l /l.l||||./ Q0 mm u 3 w ///////////AW////////// 2 m z B W 4 I, 9 a 2 w f mwv u 7 mmmwmmmmz r0l 8 Q 6 m. I 00 9 3 l/ m mm mcccc 7 7 n a o 3M5 z a. a 3 4 W. 9 w a 2 2 4 5 fllj redjfz l afer-Jan aqo Jvmes M Cumm/n ma July 18, 1950 A. J. A. PETERSON ET-AL 2,516,013

cmcum INTERRUPTER I Filed Nov. 7, 1946 2 Sheets-Sheet 2 WITNESSES: I INVENTOR 5 flflredf/Z Peferaan and ./am e5 M Curhm [n ATTORN EY Patented July 18, 195

UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER Alfred J. A. Peterson, Pittsburgh, and James M.

Cumming, Turtle Creek, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 7, 1946, Serial No. 708,412

11 Claims. 1

This invention relates to circuit breakers de signed for use with high tension power circuits, and more particularly to a circuit breaker having fluid pressure responsive operating mechanism constructed and arranged to facilitate repeated rapid opening of the breaker contacts.

In the construction of a circuit breaker of the fluid pressure operative type having a piston and piston rod operatively connected to the main contact members, various designs of control devices are available for rendering the breaker quickly responsive to a line fault, and particularly after a closing operation, to eilect rapid opening of the main contact members. By the provision of auxiliary dump valves and controlling means, such a circuit breaker can be effectively equipped for rapid open-close-open duty with both the operating piston and piston rod at all times operatively connected to the main contact members. Although a complicated and expensive latching mechanism may be required, it has also been proposed to provide means for permitting release of the entire pneumatic operating mechanism from the contact members to effect opening of the circuit under control upon indication of a fault, the selection of the mechanism desired depending largely upon the service ior which the circuit breaker is intended and the cost allowable.

Circumstances may at time render inadvisable a construction in which the entire fluid pressure responsive operating mechanism of the circuit breaker is to be released from the contact members in eiiecting a rapid opening operation, for reasons such as the difiiculty of providing lowcost latching equipment having the necessary dependability and rugged construction. On the other hand, if the circuit breaker is of the type requiring return of the fluid pressure elements, including the piston, simultaneously with each contact opening operation, it is necessary to provide means for overcoming inertia of the piston and the retarding eiiect thereon of back pressure.

It is an object of the present invention to provide an improved circuit breaker operating mechanism including a piston rod operatively connected with the usual contact members, a piston associated with the rod and means operative to release the piston from the rod for facilitating an opening operation of the circuit breaker independently of the position of the piston.

Another object of the invention is to provide an improved fluid pressure responsive operating mechanism for a circuit breaker, comprising a fluid pressure responsive clutch mechanism constituting an automatically releasable connection between the piston and piston rod.

A further object of the invention is to provide an improved circuit breaker operating mechanism of the fluid pressure responsive type, including an operating piston detachably associated with a contact operating rod, and a cylinder of sulficient length to permit operation of the piston through rapidly successive strokes in effecting a closed-open-closed-open sequence of operation.

Other objects and advantages of the invention will be apparent in the following more detailed description thereof, taken in connection with the accompanying drawings, in which:

Figure 1 is a diagrammatic view, partly in section, of the operating mechanism in a single pole unit of a fluid pressure actuated circuit breaker constructed in accordance with one form of the invention;

Fig. 2 is a fragmentary sectional view, in enlarged detail, of the automatic vent valve device shown in Fig. 1, and

Fig. 3 is a sectional view of the fluid pressure portion of a circuit breaker operating mechanism similar to that shown in Fig. l, but having a cylinder and piston constructed in accordance With a different form of the invention.

The equipment illustrated in Fig. 1 includes the operative portion of a single pole unit for a fluid pressure actuated circuit breaker, the parts being illustrated in schematic form for the purpose of simplifying the disclosure of the invention. The apparatu may comprise a suitable frame structure (not shown) supporting stationary contact elements 5 in the main circuit to be controlled, a movable resilient contact element 6 operative into bridging relation therewith and supported by a rod 1, and means for operating the movable contact element including a vertically arranged operating rod 8, which is pivotally connected by means of a pin 9 to a beam ID fulcrumed on a stationary pin ll carried by the frame structure. The end of beam 10 opposite that connected to pin 9 is pivotally connected to the upper end of rod 1 by means of a pin 52. A coil spring I3 is mounted in surrounding relationship with the movable rod 7, and may be interposed between a suitable stationary member Iii, carried by the frame structure, and a washer 16 secured to the rod I, for urging the rod '1 and contact element 6 downwardly and toward a circuit opening position.

The operating rod 8 is secured to a piston rod 8a, which, in effect, constitutes an extension of rod 8 and is slidably mounted in a suitable bore 26 formed in the upper portion of a cylinder 2|, suitably supported by the frame structure. The lower portion of cylinder 2i is preferably closed by plate 22 having atmospheric exhaust opening 23. The lower end of the piston rod 8a extends through a bore 24 formed in plate 22 for guiding purposes.

As will be hereinafter more fully explained, the piston rod 8a is adapted for cooperation with a freely mounted movable abutment or piston assembly of unique design, indicated generally by the reference character 25, which is contained in the cylinder between a pressure chamber 27 and atmospheric chamber 28. The piston assembly is constructed and arranged to respond to an increase of pressure of fluid in chamber 21 for closing the circuit breaker.

For maintaining the circuit breaker elements in circuit closing position, the circuit breaker apparatus is further provided with a transversely disposed beam 35, one end of which is journaled on a pin 31 carried by a link 32, which is, in turn, pivotally connected to a pin 33 carried by a bracket 34 extending from cylinder 2!. In actual practice, the beam 39 and link 32 may each oomprise a pair of similar elements arranged in parallel relation and secured together for insuring proper balance and strength, although in Fig. 1 only single elements thereof are illustrated. Beam 8B is operatively connected by means of a pin 36 to piston rod Be at a point above cylinder 2i and also carries, at the end opposite pin 3|, a roller 31 which is adapted to be engaged by a suitable latch mechanism 3%; for holding beam 36 and the associated elements of the circuit breaker in closed circuit position.

The latch mechanism 38, which may be of any suitable design, is illustrated in Fig. l as comprising a main latch member ll] pivotally connected to a stationary pin H secured to a bracket portion 620i the cylinder structure, a secondary latch t3 pivotally connected to the cylinder structure by means .of a pin for cooperation with the main latch member and a holding lever 35 associated with the secondary latch 4-3. The main latch member if! has a surface 23 engageable with the roller 31, and an extension #9 adapted to interlock with the upper end of latch 33, when the parts are disposed as shown in Fig. 1. In this position of the parts, it will be seen that the main latch member is prevented from clockwise movement about pin ll under the force tending to raise the end ofbeam 3B carrying the roller 31. For biasing the main latch member 30 in a counter-clockwisedirection about pin ll, there is provided a spring fail, which is interposed between a lug carried by the cylinder structure and the head of a link t2 pivotally connected to an arm of the main latch member.

For tripping the latch mechanism 33, there is provided an electroresponsive trip magnet 55 which is adapted when energized to cause upward movement of an armature carrying a plunger 55, the upper end of which is operatively aligned with a portion of the secondary latch 43. Latch 43 is normally urged into the position in which it engages the extension es of the main latch memher, through the medium of a spring 51, which is adapted to yield upon operation of the secondary latch by trip plunger 55. It will be noted that the holding lever id is inoperative when the parts are disposed as shown in Fig. l, but serves to hold the latch -53 out of interfering relation with the latch member Gil when the beam 3% and other operating elements of the circuit breaker are in trolling the supply valve mechanism 65.

circuit opening position. A coil spring 59 is interposed between the top portion of the cylinder structure and a lug 68 formed on the holding lever 45, for tilting the latter in a clockwise direction about pin 44 and causing the lug to carry latch 43 in the same direction, when the end of beam 39 carrying roller 31' is swung upwardly during a circuit opening operation of the circuit breaker. It will be noted that a lug Bl carried on the upper end of holding lever 45 is adapted to be engaged by the free end of beam 30 when that member is moved to a circuit closing position as shown in Fig. 1. Lug 66 of the holding lever is at the same time disposed in non-engaging relation with the latch A3.

For controlling the supply of compressed air or other fluid under pressure to chamber 21 in cylinder 2 l there is provided a supply valve mechanism 65, illustrated in simplified form as comprising a casing having a valve chamber 65 communicating with a suitable source of fluid under pressure by way of a supply pipe 61. Within valve chamber 66 is mounted an inlet valve 68, which is normally urged into a seated position by a coil spring 69 and controls communication from the valve chamber 66 to a passage 10 leading to chambox-'27. The valve 68 is provided with a stem H, the upper end of which extends into an atmospheric exhaust chamber 72, communication to which is controlled by a discharge alve 13 secured to the stem. An armature carried on an upper stem 14 of the valve 53 is movably disposed within an electroresponsive magnet coil 15, which is adapted to'be energized as hereinafter explained for moving the discharge valve 13 into seated position while unseating the supply valve 68.

The circuit breaker apparatus for which my invention has been devised is preferably of the type constructed and arranged for quick reclosing of the main circuit to be protected, following an opening operation in response to a line fault, and for this purpose may have associated therewith a suitable reclosing means and auxiliary control circuit therefor, as shown in Patent 2,403,082, issued to A. W. Hill et al., July 2, 1946, and assigned to the assignee of this application. As diagrammatically shown in Fig. 1, such means may include a fault responsive relay 80, a reclosing relay cl, an operating relay 82, a release relay 83, and an auxiliary switch 85 which is actuated by the piston rod 8a in accordance with movement of the contact element 6. Since these COl'llllOlllIlg elements and the auxiliary circuit are included only for the purpose of illustration and are not herein claimed as a part of our invention, it is not deemed necessary to present a detailed description. It will be understood, however, that withthe circuit breaker in its normal closed circuit position as shown in Fig. 1, the fault relay will be rendered responsive to a line fault for effecting energization of the trip coil 54, thereby releasing'the circuit breaker to permit movement of the elements thereof toward circuit opening position.

During the initial opening movement of the circuit breaker, and while piston rod 8a is'shifted downwardly, auxiliary switch is actuated thereby to effect energization of the reclosing relay al, which, in turn, becomes operative to energize the operating relay 82 to complete an energizing circuit for the electromagnet 15 con- Upon energization of the electromagnet 15 the supply valve 68 is unseated to admit fluid under pressure to the piston chamber 21, thereby efiectin re-J on the piston rod 8a.

closure of the circuit breaker. It will thus be seen that the reclosing movement of the operating piston assembly is initiated immediately after the main circuit, which the circuit breaker serves to protect, has been interrupted. Meanwhile, the operating relay 82 has been rendered effective to close a circuit efiecting energization of release relay 83 which, in turn, efiects deenergization of the circuit for the electromagnet T5. The supply valve 65 is thereby caused to cut.

ofi? further supply of fluid under pressure to the chamber 21, which is at the same time vented to the atmosphere. Such means for effecting rapid reclosure of the circuit breaker are well understood by those skilled in the art, and it will be recognized that the auxiliary control circuit just described by way of illustration may also be provided with means for insuring a subsequent reopening of the circuit breaker, if the fault condition which caused the original overload or short circuit still persists when a quick reclosin operation is completed. In addition, it will be understood that a lockout device 88 of any conventional construction may be provided in the circuit of reclosing relay 8| to prevent more than a predetermined number of automatic reclosing operations of the circuit breaker, in a manner well known in the art.

According to the invention, the piston assembly 25 is constructed and arranged to cooperate with piston rod 8a at one time for effecting a closing operation of the circuit breaker, and to release the piston rod at another time to permit free rapid movement of the circuit breaker parts in order to facilitate an instantaneous circuit opening operation. As shown in Fig. 1, the piston assembly 25 comprises a piston body 9|! slidably mounted within the cylinder 2| and subject to the pressure of fluid in chamber 21, and a relatively movable plate 9| which is held in spaced relationship with respect to the piston body through the medium of a plurality of guide rods 92. The guide rods are secured to the lower side of the piston body 90 and extend through corresponding apertures formed in plate 9|, each of the rods terminating in the head 92a engageable with the lower surface of plate 9|. Surrounding each of the guide rods 92 is a coil spring 93 which is interposed between the plate 9| and the piston body 90 for normally urgin these elements apart. Both the piston body 9|) and plate 9| are provided with central openings through which the piston rod 8a is slidably fitted. Formed on the lower side of the piston body 90, concentrically of the piston rod opening therein, is an annular collar 95 having an inclined interior surface 96, within which are mounted a plurality of ball clutch elements 98. These ball clutch elements 98 are adapted to be driven into gripping relation with piston rod 8a upon sudden downward movement of the piston body 90 in response to an increase of pressure of fluid in chamber 2?.

For biasing the piston assembly 25 upwardly and toward its release position as shown in Fig.

l, a coil spring 99 is interposed between the 010-,

sure plate 22 of the cylinder and the plate 9|, it being understood that this spring when ful1y expanded is long enough to hold the plate 9| at its uppermost position as illustrated, while the springs 93 are permitted to maintain piston body 99 in engagement with a stop shoulder I09 formed on the wall of chamber 2?. The ball clutch elements 98 are thus at the same time allowed to rest loosely on plate 9| without exerting any force In order to insure venting of chamber 2! at an adequate rate in response to tripping of the circuit breaker, particularly after reclosing of the mechanism on a still continued fault in the main line being protected, it may be found advisable to provide an auxiliary dump valve mechanism N35. The dump valve mechanism i515 may consist of any one of a number of conventional electroresponsive vent valve devices as, for example, the arrangement shown in the copending application of Gilbert J. Easley et al., Serial No. 545,- 438, filed July 18, 1944, now Patent No. 2,470,608 granted May 17, 1949, and assigned to the assignee oi the instant application, and is illustrated as comprising a casing Hi6 mounted on the upper portion of cylinder 2| and having a discharge chamber lill communicating through a passage I08 with piston chamber 21. Operatively mounted in a suitable bore formed in casing H16 is a valve member it which, as is best shown in Fig. 2, is adapted to control communication from the discharge chamber Hi! to exhaust openings l formed in the casing. A pilot valve H3 is provided for admitting fluid under pressure from discharge chamber llll to a pressure sm'face H4 on the valve member Mil in order to efiect movement thereof, against the force of a spring H5, to establish communication from the discharge chamber to the exhaust openings Ill. The pilotvalve i3 is normally held in seated position and is arranged to be unseated upon energization of electromagnet lit, the circuit for whichmay be under the control of fault responsive relay 8B.

In order to explain the operation of the elements of the circuit breaker apparatus constituting my invention, it Will be assumed that the various parts thereof are intially disposed in the circuit closing position as illustrated in Fig. 1. With the parts in this position, it will be understood that the piston chamber 2? is connected to the atmosphere by way of a communication controlled by the unseated valve 73, and that the piston assembly 25 is maintained in its uppermost or released position with the ball clutch elements 98 disposed loosely with respect to piston rod 811.

When a predetermined overload or short circuit occurs in the main circuit through contact elements 5 and 6, the fault responsive relay 89 is immediately energized to effect energization of the trip magnet 54. The plunger 55 is thereby forced upwardly to release the latch mechanism 38 which, in turn, frees beam 39. The spring i3 is thereupon rendered efiective to force the movable contact 6 downwardly to interrupt the main circuit, the highspeed of this operation being in large measure due to the fact that piston rod 8a is carried upwardly independently of piston assembly 25. It will be apparent that response to such a tripping operation of the circuit breaker is thus accompanied by quick movement of a minimum number of parts consisting of piston rod 3a, beam 36, operating rod 8, beam l6, rod 1 and the movable contact element 6.

As hereinbefore explained, the piston rod 8a in moving upwardly in the course of the circuit opening operation actuates the auxiliary switch 95 to intiate the usual sequential operation of the associated relays of the automatic reclosing circuit means, including reclosing relay 8| and operating relay 82, with the result that electromagnet 15 is energized for operating the supply valve mechanism to admit fluid under pressure to the piston chamber 21.

omitted to simplify the disclosure.

7 Upon the sudden increase of pressure "of fluid in 'piston'chamber'zl the piston-body 90 is quick- 'ly forced downwardly compressing thesprings 9-5 and 'intially moves relatively to the plate 91 which is subject to the force of spring 99, so that the ball clutch elements 98 are wedged between the inclined annular surface 96 and the adjacent surface of piston rod "811, which is thereupon carried downwardly alongwith the elements of the piston assembly. Piston assembly 25 is thus rendered efiective to move the movable contact element 6 "into engagement with the stationary contact 'element'5 through the medium of piston rod'8a operatingrod-B, beam Ill and rod "I.

'When the aforementioned operating elements of the circuit breaker apparatus reach circuit closing'position, the auxiliary switch 85 is positioned to complete the energizing circuit for the release relay 83, which, in turn, effects deenergization of the 'supply'valve electromagnet 75. The supply valve mechanism 65 is'thereby operated to discharge fiuid under pressure from'piston chamber 21, and upon the reduction'of pressure acting downwardly on piston body 90, the springs 93 .again become effective to move the'piston body away "from the plate 9| "for releasing the ball clutch elements 98 from gripping relation with piston rod 8a. The piston assembly 25 may then be shifted upwardly with relation to the piston rod 3a under the force exerted byspring 99.

In the event that the circuit breaker "should be thus reclosed to complete'the'main circuitwhile a fault still continues to be present therein, the consequent reenergization of the fault responsive relay 80 will initiate another circuit'opening operation of'the circuit'breakerin the manner'already described. At'the same time,'however, the electromagnet I I6 of the dump valve-mechanism I 95 will alsobe'energized'to cause the'dump valve to accelerate discharge of fluid under pressure from'the piston chamber 21 so as'to'render the piston assembly '25 instantly effective to release the piston rod 3a. Sucha reopening operation of the circuitbreaker willthus be accomplishedat'a maximum rate ofspeed, regardless of any re-- maining back pressure which might be acting against piston assembly 25.

Referring to Fig. "3 of the drawings, there is illustrated an operating cylinder "assembly for a circuit breaker embodying features o'fthe inventionin a different form, certain elements of the apparatus shown in Fig. '1 'having been In Fig. 3, a cylinder I2! is provided, having a construction generally similar lto'that of the cylinder '2 [shown in Fig. '1 but having .considerablyjgreater length in order to permit a correspondingly increased traverse ofthe associated piston assembly therein, "indicated generallyby the'ireference character "I25. Associated with cylinder I'2I are'other'parts of the circuit breaker "apparatus including :operating rod *8, beam"30, trippingmec'hanism 38 and supply valve mechanism 65. The "various elements of these parts "which correspond to those already described in connection vvithFig. 1 are designatediin'Fig. 3' by the same reference char- .acters.

Slidably mounted "in cylinder I2I is 'a piston rod [119a which corresponds to piston rod-8a in Fig. l, but'is of greater length to correspond with the dimension of cylinder I2I. The piston rod 108a carries .an annular collar I69 on which is seatedthelower endfiof a coil'spring H2 forurging the piston 'assembly'l25 upwardly.

According to the form of the invention'shown and I I9 for urging those elements apart.

fit into a suitable annular groove formed in the lower surface of the piston member IE9. Both piston members H8 and II9 are provided with "central apertures through which "the piston rod I98a is slidably fitted. A plurality of coil springs I29 are interposed between piston members H8 Each of these springs is coiled about one ofa plurality of vertically disposed guide rods I22, the upper ends of which are secured to the "piston member I I8, and'thelower ends of which'slidably engage in suitable apertures formed in piston member H9 and terminate in enlarged portions for supporting the latter member. A concentrically disposed annular collar I23 formed on the piston member I I9 is provided with an inclined interior surface I25, which is spaced away from the sur- -race of the piston rod IIlBa a sufficient distance to receive a plurality of wedge elements I 26. The wedge-elements I29 are normally loosely disposed between the inclined surface I25 and piston rod 1198a, and are adapted to be engagedby the lower surface of piston member II8 when the latter is moved downwardly under pressure of fluid supplied to piston chamber 21.

In operation, when the electromagnet 54 associated with the *latch mechanism 38 is energized in'response to development of a fault in the main line'undercontrol of the circuit breaker apparatus, the latch -mechanism is operated in the usual manner to release beam 39, thereby permitting rapid upward movement of operating rod '8 and piston rod 198a. As hereinbefore explained, suchupward movement of the operating "rod 8 is accompanied by a circuit opening operation of the circuit breaker.

Uponsubsequent operation of the supply valve mechanism '65 to supply fluid under pressure to piston chamber 2'! inorder to effecta'reclosing operation of the circuit breaker,'the piston member I It is driven downwardly with sufficient force to cause the wedge elements I29 to move into locking engagement with the piston rod IBM. The piston assembly I25 is thereafter moved downwardly under pressure of fluid in chamber 2! and carries with it piston rod IIIBa and operating rod *8 for effecting closure of the 'circuit breaker in the-usual manner. Assuming that the piston assembly I25 moves approximatelyto the middle portion of cylinder I2I incompleting the reclosing operation of the circuit breaker, and that the circuit breaker is thus recl'osed while the fault in the main line still persists-the electromagnet 54 is consequently again energized for tripping the circuit breaker latch mechanism 38. The dump valve mechanism I is energized at the same instant, "as hereinbefore explained, for effecting 'qu'ick'reduction'in thepressure of 'fluid in chamber '21, so that the piston members I I8 and H9 can be immediately moved apart by springs I20 sufficiently to release wedge elements 126 from the piston rod IOSa. With the piston rod I08a thus free for rapid upward movement independently of the piston assembly I25 and even though some fluid pressure remains in piston chamber 21, a rapid reopening of the circuit breaker is insured.

When the circuit breakerapparatus has-thus been operated to reopen the main circuit, and before the piston assembly l25 has had time to traverse the distance from its intermediate position within cylinder 12! to its normal released position at the upper end of the cylinder, another reclosing operation of the circuit breaker is automatically accomplished by subsequent reenergization of supply valve electromagnet 15 in the usual manner. It will be apparent that when the supply valve element 68 is thus again unseated, the further supply of fluid under pressure to piston chamber 21 again effects operation of piston member H8 to drive wedge elements I26 with looking engagement with piston rod l08a, whereupon additional downward travel of piston assembly l through the lower portion of cylinder [2i effects a second reclosing operation of the circuit breaker. It will thus be seen that additional length of cylinder 12!, in association with the automatically releasable clutch arrangement of piston assembly I25 with respect to piston rod 108a, renders the circuit breaker apparatus particularly eflicient in a "closed-openclosed open sequence of operations.

From the foregoing description of our invention, it will be apparent that by reason of the fact that the automatically releasable and independently movable piston assembly constructed in accordance with our invention has the inherent tendency to return. to its normal position at the upper end of the cylinder in response to any reduction in pressure therein, the volume of fluid under pressure required for repeated operation of the piston assembly, as in eiiecting a rapid reclosure of the circuit breaker, is reduced to a minimum. The novel piston and clutch arrangement also insures extremely rapid response of the circuit breaker to a line fault, without necessitating the provision of unduly complicated and expensive auxiliary equipment.

The improved circuit breaker apparatus embodying the features of construction herein dis-- closed may thus be utilized to advantage in existing circuits for bettering service performance under heavy load conditions demanding substantially uninterrupted power supply.

We claim as our invention:

1. In a fluid operated. circuit breaker, movable contact means having open circuit and closed circuit positions, a cylinder, means for supplying and releasing fluid under pressure to and from said cylinder, operating means for said movable contact means, a movable abutment operatively mounted in said cylinder and subject to the pressur of fluid supplied thereto for actuating said operating means to move said contact means to closed position, and clutch means associated with said abutment for at times releasing same from said operating means to render the latter movable to open position independently of said abutment.

2. In a fluid operated circuit breaker, movable contact means having open circuit and closed circuit positions, operating means for said movable contact means including an operating rod, a cylinder, means for supplying and releasing fluid under pressure to and from said cylinder, a movable abutment operatively mounted in said cylinder cooperating with said operating rod and subject to an increase in fluid pressure for actuating said contact means to said closed position, and releasable coupling means associated with said abutment and responsive to a reduction in fluid pressure for releasing said abutment from said operating rod to render said movable contact means operable to said open position independently of said abutment.

3. In a fluid operated circuit breaker, movable contact means having open circuit and closed circuit positions, operating means for said movable contact means including an operating rod, a cylinder, means for supplying and releasing fluid under pressure to and from said cylinder, a movable abutment operatively mounted in said cylinder and subject to variations in the pressure of fluid therein for controlling said movable contact means, and coupling means in said cylinder responsive to an increase in fluid pressure in said cylinder for coupling said abutment to said operating rod to move said contact means to said closed position and responsive to a reduction in fluid pressure for releasing said abutment from said operating rod to render said contact means operable to said open position independently of said abutment.

4. In a fluid operated circuit breaker, movable contact means having open circuit and closed circuit positions, a cylinder, means for supplying and releasing fluid under pressure to and from said cylinder, operating means extending into said cylinder and connected to said movable contact means, a movable abutment operatively mounted in said cylinder cooperating with said operating means and subject to variations in the pressure of fluid therein for controlling said movable contact means, and clutch means responsive to an increase in fluid presure in said cylinder for coupling said abutment to said operating means to render said abutment operable to move said contact means in one direction and responsive to a reduction in fluid pressure for releasing said abutment from said operating means to render said contact means movable in the opposite direction independently of said abutment.

5. In a fluid operated circuit breaker, movable contact means having open circuit and closed circuit positions, a cylinder, means for supplying and releasing fluid under pressure to and from said cylinder, operating means extending into said cylinder for moving said movable contact means, a movable abutment operatively mounted in said cylinder cooperating with said operating means and subject to an increase in fluid pressure for moving said contact means in one direction, spring means constructed and arranged to move said contact means in the other direction, and means responsive to a reduction in pressure of fluid in said cylinder for releasing said operating means from said abutment to render said contact means operable by said spring means.

6. In a fluid operated circuit breaker, movable contact means having open circuit and closed circuit positions, a cylinder, connecting means extending into said cylinder and connected to said movable contact means, means for supplying and releasing fluid under pressure to and from said cylinder, a movable abutment operatively mounted in said cylinder cooperating with said connecting means and subject to an increase in fluid pressure for moving said contact means in one direction, spring means constructed and arranged to move said contact means in the other direction, and clutch means responsive to an increase in pressure of fluid in said cylinder for rendering said connecting means operable by said abutment and responsive to a reduction in pressure of fluid in said cylinder for rendering said contact means operable by said spring means.

7. In a fluid operated circuit breaker, movable contact means having open circuit and closed circuit positions, a cylinder, means for supplying and releasing fluid under pressure to-and from said cylinder, a connecting rod slidably mounted in said cylinder and operatively connected with said movable contact means, a movable abutment operatively mounted in said cylinder for cooperation with said connecting rod, clutch means carried by said abutment and operable at one time to grip said connecting rod to efiect movement of said contact means to the closed position by said abutment, said clutch means being operable at another time to release said connecting. rod for permitting operation independently of said abutment.

8. In a fluid operated circuit breaker, movable contact means having open circuit and closed circuit positions, a cylinder, means for supplying and releasing fluid under pressure to and from said cylinder, a connecting rod slidably mounted in said cylinder and operatively connected with said movable contact means, a movable abutment operatively mounted in said'cylinder for cooperation with said connecting rod, and clutch means carried by said abutment and automatically operative into and out of engagement with said connecting rod in accordance with variations of pressure of fluid in said cylinder, whereby said contact means is rendered operative by said abutment at one time and independently thereof at another time.

9. In a fluid operated circuit breaker, movable contact means having open circuit and closed circuit positions, a cylinder, means for supplying and releasing fluid under pressure to and from said cylinder, a connecting rod slidably mounted in said cylinder and operatively connected with said movable contact means, a movable abutment operatively mounted in said cylinder for cooperation with said connecting rod, spring means for moving said contact to open position free of said abutment, a clutch means carried by said abutment, said clutch means being operative upon an increase in fluid pressure in said cylinder to grip said connecting rod for rendering said abutment effective toactuate said contact means to the closed position.

10. In a fluid operated-circuit breaker, movable contact means having open circuit and closed circuit positions, a cylinder, means for-supplying and releasing fluid under pressure to and from said cylinder, a connecting rod slidably mounted in said cylinder and operatively connected with said movable contact means,,a movable abutment operatively mounted in said cylinder for cooperation with said connecting rod, a clutch means carried by said abutment, said clutch means being operative upon an increase in fluid pressure in said cylinder to grip said connecting rod for rendering said abutment effective to move said contact means in one direction. and operative to release said connecting rod upon a sudden reduction of pressure of fluid in said cylinder.

11. In a fluid operated circuit breaker, movable contact means having open circuit and closed circuit positions, a cylinder, means for supplying and releasing fluid under pressure to and: from said cylinder, an operating rod operatively related to said movable contact means and slidable in said cylinder, a movable abutment operatively mounted in said cylinder and subject to an increase in fluid pressure for moving said contact means in one direction, clutch means responsive to an increase in pressure to operatively connect said abutment to said operating rod, spring means constructed and arranged to move said contact means in the other direction, biasing means for urging said abutment toward a normal starting position, and said clutch means being operable to free said abutment from operative connection with said operating rod in response to a reduction in pressure of fluid in said cylinder, whereby said contact means is then rendered operative solely by said spring means while said abutment is released for movement to said normal position.

ALFRED J A. PETERSON. JAMES M. CUMMING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 686,352 Sellers et al Nov. 12, 1901 2,205,346 Clench June 18, 1940 2,399,328 Cumming Apr. 30, 1946 

